But if Moto Voice is set up, it might be inappropriately preventing other apps from using the microphone. Can you try turning off Moto Voice in its settings, or disabling it in Settings>Apps​?

I've just now had the time to look into this. I've disabled Moto voice and then gone into the Google app - settings - voice - "OK Google" detection. Right now, only the 'from the Google app' and while driving options are on. When I select the 'from any screen' option, I get the prompt to setup the phrase "OK Google." It keeps stating that the microphone can't be used and to restart the device. Restarting and then trying again doesn't work.

The OK Google didn't work before Nougat and it doesn't work after. I've verified that the Google app has permission for the microphone and that the app isn't disabled. Interestingly, even though the Moto app is disabled, I can still say the launch phrase "OK Moto z" and it will open the Google search.

I had issues setting up Moto voice and ultimately had to do the launch phrase in the car so that it would work properly. I just would like to know why the Google app keeps saying it can't use the microphone.

Obviously the microphone works for Moto voice, so that's not the issue.